1. Field of the Invention
The present invention relates generally to power distribution equipment and, more particularly, to a clamp for clamping a wire to a conductor of a circuit breaker.
2. Description of the Related Art
Numerous types of circuit breakers are known and understood in the relevant art. Among the purposes for which circuit breakers are provided is to interrupt electrical current on command or under certain defined circumstances. Generally stated, most circuit breakers include a line conductor connected with a power source and a load conductor connected with an electrical load, and further include a current interruption system interposed between the line conductor and the load conductor to interrupt current as needed. The current interruption system typically includes an operating mechanism that separates a set of separable electrical contacts to interrupt current from flowing therethrough, and further includes a trip unit operatedly connected with the operating mechanism. The trip unit triggers the operating mechanism to separate the electrical contacts during the specified overcurrent, undervoltage, or other conditions. In multi-phase circuit breakers, the operating mechanism typically includes a crossbar that simultaneously separates several sets of separable contacts to simultaneously interrupt current through all of the phases of the circuit breaker.
In many power distribution systems, the electrical load is in the form of a wire that is connected with the load conductor. Moreover, depending upon the configuration of the circuit breaker, the power source can likewise be in the form of a wire that is connected with the line conductor of the circuit breaker. Known wires typically are either of a solid or stranded configuration, both of which have an elongated cylindrical configuration. In order to electrically conductively connect such wires with the load and/or line conductors of the circuit breaker, the wire must be engaged against the conductors with an appropriate clamp. While numerous types of clamps are generally known, such clamps have not, however, been without limitation.
As is known in the relevant art, line and load conductors of circuit breakers are generally of an elongated configuration with a rectangular cross section such that the conductor provides a substantially planar engagement surface against which the clamp electrically conductively engages the wire. Such clamps typically each include a fastener and a connection plate, whereby the fastener in configured to apply appropriate forces through either or both of the clamp and the conductor to electrically conductively engage the wire with the conductor. The clamps typically are structures that are separate and independent of both the circuit breaker and the conductor, and are made as separate components for reasons of versatility and cost-effectiveness, as well as for other purposes.
The separate nature of the clamp undesirably permits the connection plate thereof to be movable with respect to the conductor such that a connection surface of the connection plate can become non-parallel with the engagement surface of the conductor, as can be seen generally in FIG. 1. Such a non-parallel relationship typically results from a shifting of the clamp with respect to the conductor during and/or subsequent to tightening the fastener. Non-parallel situations almost always occur during tightening of the fastener when the fastener is centrally disposed on the clamp and only a single solid wire is electrically conductively engaged with the conductor. Such a non-parallel relationship between the engagement surface and the connection surface increases the likelihood that the wire may eventually become undesirably loosened from between the conductor and the connection plate and thus less than fully electrically engaged with the conductor, which can result in arcing and a hot spot.
As can be understood from the conductor and clamp arrangement depicted in FIG. 1, the conductor C and the connection plate I both apply forces normal thereto to the wire W when the fastener F is tightened. Since the conductor C and the connection plate I are non-parallel, the normal forces, when combined, provide a resultant force on the wire W in a direction away from the fastener F. The normal forces also create frictional forces that resist movement of the wire W in the aforementioned direction away from the fastener. Depending upon the configuration of the conductor C, the connection plate I, and the wire W, the wire W will tend to become loosened from between the conductor C and the connection plate I if the resultant force on the wire overcomes the frictional forces applied thereto. It is thus desired to provide a clamp having a connection plate that is specifically configured such that the resultant force on the wire does not overcome the frictional or other retentive forces on the wire W, which advantageously will resist the wire W from becoming loosened or less than fully electrically conductively engaged with the conductor C.
In accordance with the foregoing, a terminal wire clamp is provided with a fastener and a connection plate, in which the connection plate has a connection surface that is formed with a retention channel, and in which the retention channel is structured to receive a wire therein and resist movement of the wire after the wire has electrically conductively engaged a conductor.
An object of the present invention is to provide an improved clamp for use in electrically conductively engaging a wire with a conductor.
Another object of the present invention is to provide a clamp formed with a retention channel that is structured to receive a wire therein and resist movement of the wire after the wire has electrically conductively engaged a conductor.
Another object of the present invention is to provide a clamp having a connection plate and a fastener, in which the connection plate is formed with a retention channel that is offset from the fastener.
Another object of the present invention is to provide a circuit breaker having a conductor and a clamp, in which the clamp is formed with a retention channel and is structured to electrically conductively engage a wire with the conductor, the retention channel being structured to resist movement of the wire after the wire has engaged the conductor.
As such, an aspect of the present invention is to provide a terminal wire clamp structured to electrically conductively engage a wire with a conductor, the general nature of which can be stated as including a fastener and a connection plate, the fastener and connection plate being cooperable with one another to electrically conductively engage the wire with the conductor, the connection plate having a connection surface, the connection surface including a first retention channel formed into the connection plate, and the connection surface is structured to engage the wire and at least partially receive the wire in the first retention channel, with the first retention channel being structured to resist movement of the wire when the connection plate engages the wire with the conductor.
The connection plate may include an engagement member having a primary portion and a first rib, with the primary portion including a substantially planar primary surface, and with the first rib including an elongated first rib surface, the first rib surface protruding outwardly from the primary surface and extending at least partially in a direction non-parallel with the first retention channel. In such a configuration the connection surface includes the primary surface and the first rib surface, with the first retention channel being formed into the first rib.
The engagement member may include a second rib, with the second rib having an elongated second rib surface protruding outwardly from the primary surface, in which the first retention channel is formed across both the first and second ribs. The first and second retention channels are advantageously tangent to the primary surface. The first and second ribs may be first and second embossments.
Another aspect of the present invention is to provide a circuit breaker, the general nature of which can be stated as including a line conductor, a load conductor, an operating mechanism operatively interposed between the first and second conductors, and a terminal wire clamp structured to electrically conductively engage a wire with one of the line and load conductors, in which the terminal wire clamp includes a fastener and a connection plate that are cooperable with one another, and in which the connection plate has a connection surface including a first retention channel formed into the connection plate. The terminal wire clamp is structured to cooperate with a fastener to engage the wire with the conductor, and the connection surface is structured to engage the wire and at least partially receive the wire in the first retention channel, with the first retention channel being structured to resist movement of the wire when the connection plate engages the wire with the one of the line and load conductors.